What do you mean by offset printing? Based on your scan, your stamp is a poorly perforated Scott 331 or 374. Both of those stamps were intaglio printed which means that designs were etched into metal and not offset printed which means lithographic printing.
Bill - I think Friendly City Stamps is referring to the poor perforation job as being offset from the design, not that the stamp was printed using the offset printing method.
Friendly City Stamps - the wide margins at the right and bottom of your stamp was caused by the sheet of paper being poorly aligned when it was fed into the perforating machine. It is not an error - just a poorly centered stamp.
Hi Friendy, and welcome to the forum. Offset is a printing technique - what you mean to say is probably mis-perforated. The sheet was probably not fed into the perforator correctly, something that is not uncommon with stamps of the era.
Thank you gentlemen for your replies. What I was referring to was the design being offset and I now see how the paper not being aligned as it was fed into the machine would cause this to happen. Thanks again!